# 3 bit input(A,B,C) 7 segment display help

Discussion in 'Homework Help' started by Ajdawson94, Nov 19, 2018.

1. ### Ajdawson94 Thread Starter New Member

Nov 19, 2018
3
0
HI im a first year student and im only just starting out, in the examples my professor gave me he uses bcd inputs A,B,C,D to come up with a truth table standard 0-9 display, however i have been asked to use a 3 bit input to draw a truth table for a 7 segment display that spells the word BLUEFISH. how would the actual truth table to drive segments a-g look like? would it look like this?

any help is greatly appreciated

2. ### MrChips Moderator

Oct 2, 2009
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As an example, which segments must be lit to show "F"?

Apr 5, 2008
19,678
4,047
4. ### dl324 AAC Fanatic!

Mar 30, 2015
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Welcome to AAC!
That's one possible implementation. If you ever have the chance of needing to display the number 8, you might choose a different combination of segments for B.

Since this is homework, you need to show your work before we can attempt to guide you to a solution

5. ### Ajdawson94 Thread Starter New Member

Nov 19, 2018
3
0
it says to Draw the truth table to drive segments (a-g) of the display. then Using the truth table you have obtained, draw Karnaugh maps for each segment to find the minimised logic expression. i can do the karnaugh maps and find the expression yet the truth table is giving me issues.
each letter of the BLUEFISH corresponds 0-7 in decimal digit.
0->’B’, 1->’L’, 2 ->’u’, 3-> ‘E’, 4->’F’, 5->’i’, 6->’S’, 7->’h
so digit 0 needs all segments lit to produce B and so on.

from that i produced the table in my original post, with it being 3 bit input would i be correct in assuming that i only do a,b,c and not the standard 4 bit BCD a,b,c,d.
i know that B can be shown in an alternative format however i have been asked to do so as shown in the image

Last edited: Nov 19, 2018

Apr 5, 2008
19,678
4,047
Hello,

The give table is not complete.
I would use the leading zeros too.
You could do this by placing A, B and C in separate coloms.

Bertus

7. ### dl324 AAC Fanatic!

Mar 30, 2015
8,516
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You didn't state that requirement in the first post. It would be helpful if you posted the complete text for the problem.

8. ### WBahn Moderator

Mar 31, 2012
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You have seven different logic problems. You have one logic for each segment. Treat them as separate 3-input, 1-output logic problems. Don't make it harder than it is.

9. ### Ajdawson94 Thread Starter New Member

Nov 19, 2018
3
0
thanks i think i get it now thankyou all for the help

10. ### absf AAC Fanatic!

Dec 29, 2010
1,924
542
Wouldn't it look better in All Caps?

dl324 likes this.